Packing the threads is easy on a graphite rod is easy because the blank is very smooth. If a bamboo blank is sanded smooth, it is also easy to pack the threads.
Some people wrap first, some people varnish first.
As far as turning the hex shaped blank while wrapping, your wrapper will determine how easy it is. If you wrap with the blank in a steep angled groove, it will be harder to turn anything that is not round.
My wrapper isn't a "V" shape, it's more rounded where the blank rests. Hex shaped blanks feel a little bumpy, but not bad at all.